What Does the Science Actually Say on Artificial Sweeteners?

Very few topics in nutrition are as controversial as whether or not artificial sweeteners are bad for you. Surely, you can’t just sacrifice calories without sacrificing taste, can you? That’s not how the world works. You can’t have your artificially-sweetened cake and eat it too. That’s cutting corners. There have to be consequences for cutting corners, right?

Even if you avoid diet soda, there are very few protein powders without at least one kind of “non-nutritive sweetener” on the ingredients list. Today we’re going to talk about the three most common: sucralose, acesulfame potassium, and aspartame.

Editor’s note: The content on BarBend is meant to be informative in nature, but it should not be taken as medical advice. The opinions and articles on this site are not intended for use as diagnosis, prevention, and/or treatment of health problems. Speak with your physician if you have any concerns.

Sucralose and Your Health

Also known as Splenda®, sucralose remains the world’s most popular artificial sweetener and generates over 30 percent of the industry’s total revenue. Most of it isn’t broken down by the body when you eat it, so it’s usually considered noncaloric.

Criticism of sucralose focuses on the idea that it may increase your appetite, which would make it a pretty ineffective way to reduce calories. A famous 2008 study looked at 3,682 overweight people in San Antonio and found that those who drank more than three diet sodas a day were twice as likely to become overweight or obese over an eight-year period.(1) Another published in Diabetes Care concluded that people who drank diet soda at least once a day were 67 percent more likely to develop Type 2 diabetes.(2)

But those studies are observational. Maybe people who gain weight are just more likely to drink diet soda. If you’re health conscious, you’ve probably heard people swear that diet soda is bad for you and there might be a better chance that you avoid it.

They aren’t the only studies to have suggested that sucralose may mess with the hunger response, though. An influential one published in Cell Metabolism in 2016 proposed that chronic intake of sucralose (or other artificial sweeteners) can desensitize you to sweetness — that is, weaken your body’s “belief” that sweet food is a good source of energy.(3) If your body doesn’t think you’re getting calories from sweet food then maybe it will trigger your appetite instead of making you feel sated.

A huge but: that study drew its conclusions by giving sucralose to flies and mice. We don’t have the same data for humans.

Fortunately, there is research on sucralose that is more specific to our questions here. A much more useful meta analysis of 15 randomized controlled trials — widely considered the gold standard in quality as far as studies go — found no associations with low-calorie sweeteners like sucralose and weight gain.(4) Instead it found there’s a good chance swapping caloric drinks for non-caloric drinks might produce modest weight loss. At the risk of generalizing, it’s generally good to look for meta analyses and randomized controlled trials when trying to inform yourself about a controversial subject.

And as for your insulin levels? It probably has no impact, but it might depend. One small study of 17 obese people published in Diabetes Care found that sucralose increased blood sugar and insulin by about 18 percent.(5) But a lot more studies of people at healthier body weights have found no impact on insulin at all.(6)(7)(8) If you seldom consume sucralose or you’re overweight, it might spike insulin a little. Maybe. Maybe. But we spike our insulin with our food all day, that’s not necessarily a bad thing for everyone. (Of course, this may not apply to certain people with diabetes or other conditions.)

“Sucralose appears to be relatively safe in humans, at least in the data I’ve seen, and the amount used is so super small,” says Dr. Mike T. Nelson, CSCS, an adjunct professor at the Carrick Institute whose PhD focused on metabolic flexibility. “In a lot of the sucralose research when you look at the dosage, it’s a massive dose. The amount of sucralose you need in most products is so tiny.”

So Is Acesulfame Potassium Bad for You?

“Out of all of the artificial sweeteners I have to worry about, that’s the only one that makes me a little concerned,” says Dr. Nelson. “But I’d be hard pressed to pin a ton of hard human data on it. There’s some interesting animal data, though.”

He’s right there. Also called Sunett, Sweet One, or Ace-K, early studies of rodents conducted in the 1970s declared it a carcinogen, and while those studies were later found to be not all that rigorous, there are still some curious data points out there. More rodent studies published in the late 1980s found Ace-K increases insulin levels and a 2013 one concluded that daily doses over 40 days caused memory problems.(9)(10)(11)

But the FDA has approved it, and all of those studies exceeded the FDA’s recommended daily limit, which is 15 milligrams per kilogram of bodyweight per day. (There’s good reason to believe those studies are the reason for the limit.) Fifteen milligrams per kilogram is about the amount of sweetness you’d get from half a pound of sugar. You’re unlikely to be consuming that much and again, those studies were all on rodents.

Truthfully, we do need more research on humans before we have a good idea of exactly how Ace-K might affect your insulin. (Just keep in mind that for the vast majority of people, again, an insulin spike isn’t necessarily a bad thing.)

“It’s not horribly bad, but I don’t know, if I look at labels that’s the sweetener that makes me steer away a bit,” says Dr. Nelson. “But personally, I’ve used it once in a while and I don’t lose a ton of sleep about it.”

The Controversy Over Aspartame

Aspartame, also called Equal® and Nutrasweet®, remains what may be the most controversial artificial sweetener, so much so that Diet Pepsi bowed to pressure to remove it from their line in 2015… before reversing course and putting it back in in 2018.

“There’s no scientific reason for [avoiding it], but people are somehow worried about aspartame,” Pepsi’s CEO Inidira Nooyi said at the time. Is she right?

Much of the hubbub about aspartame came about when some rodent studies found links with cancer, and a recent one published in 2006 in Environmental Health Perspectives that linked it with a statistically significant increase in the incidence of malignant tumors, lymphomas, and leukemias among rats.(12) The authors wrote,

carcinogenic effects are also evident at a daily dose of 20 milligrams per kilogram of body weight (mg/kg), notably less than the current acceptable daily intake for humans.

It sounds damning, but the fact is that the U.S. Food and Drug Administration (FDA), United Nations Food and Agriculture Organization, World Health Organization, American Heart Association, and American Dietetic Association have all signed off on aspartame. Again, with these topics you need to look at more than a couple of studies, and that’s what they did.

Aspartame is one of the most exhaustively studied substances in the human food supply, with more than 100 studies supporting its safety.

They say that the safe limit is 50 milligrams per kilogram of bodyweight, so 18 cans of soda per day if you weigh 150 pounds.

Meanwhile the European Food Safety Authority (EFSA) looked at over 600 datasets and found no reason to take it off the market either, setting their limit at 40 milligrams per kilogram.

Harvard once promoted a study that found a link with a daily diet soda to cancer, then retracted their support when some odd inconsistencies surfaced, like the fact that the same data found a greater increase in cancer risk among people who just drank regular soda.

Right now, the data just isn’t compelling enough to say aspartame will up your cancer risk, nor is there good human evidence to suggest that it increases your appetite.(13)(14)(15)

Note that people with phenylketonuria, a condition where you can’t process the amino acid phenylalanine, can’t process aspartame. But that amino acid is also in beans and all animal products so if you eat them, you’re likely OK with aspartame. (If you have any questions on this, please speak with your medical professional.)

Artificial Sweeteners and the Gut

What about all those headlines that artificial sweeteners are bad for your gut microbiome — that’s the trillions of bacteria in your digestive tract that help you break down food, absorb nutrients, manage insulin sensitivity, and maybe even promote immunity and mental health?(16)(17)(18)(19)

One of the most influential studies in recent memory was published in Molecules in September 2018 and it concluded that sucralose, aspartame, and acesulfame potassium all caused bacteria tested to get “stressed,” which they concluded as meaning the sweeteners had a “toxic effect” on belly bacteria.(20) Google “artificial sweeteners gut” and you’ll see dozens of headlines claiming this study definitively proved diet soda is nuking your microbiome and compromising your health.

The conclusion had a lot of potential issues, though. Firstly, they only tested a few strains of E. Coli bacteria in petri dishes, but our guts have millions of different bacteria squirming around in them and contributing to our health. They also used really high concentrations of sweeteners: about eight times the amount of aspartame you’d get in a liter of Diet Coke, or about 100 packets’ worth of Equal.

That’s not the only study to look at this, but it’s untrue to say Splenda and Equal definitely harm your gut. The human studies just aren’t there right now.

The Takeaway

We know appeals to authority aren’t the best way to conduct science journalism, but the overwhelming majority of rigorous studies, meta analyses, and national governing bodies don’t have an issue with consuming any of these three artificial sweeteners at moderate levels.(21)

Some people experience headaches from artificial sweeteners. That’s an excellent reason to avoid them. Some people who need to strictly manage their blood sugar, maybe, could potentially find they cause insulin spikes. That’s another great reason for those individuals to ditch them. Just don’t like the taste? Just don’t like artificial foods? Look, no one’s forcing you to drink diet soda.

But while there is some research suggesting they could cause issues the consensus is that there’s no need to lose sleep over them. Though to be fair, it looks like some more research on acesulfame potassium wouldn’t be a bad idea.

Dr. Nelson says he just goes with the “common sense” approach: given the hundreds of millions of dollars worth of diet soda consumed each year, it seems unlikely that artificial sweeteners are as bad as some headlines claim.

“If everyone’s out there licking arsenic and dropping dead, we’ll figure out pretty soon that’s bad,” he adds. “But artificial sweeteners are probably not as bad as you think. But that’s common sense, not a scientific approach.”

Nick is a content producer and journalist with over seven years’ experience reporting on four continents. His first articles about health were on a cholera outbreak in rural Kenya while he was reporting for a French humanitarian organization. His next writing job was covering the nightlife scene in Shanghai. He’s written on a lot of things.

After Shanghai, he went on to produce a radio documentary about bodybuilding in Australia before finishing his Master’s degrees in Journalism and International Relations and heading to New York City. Here, he’s been writing on health full time for more than five years for outlets like BarBend, Men's Health, VICE, and Popular Science.

No fan of writing in the third person, Nick’s passion for health stems from an interest in self improvement: How do we reach our potential?

Questions like these took him through a lot of different areas of health and fitness like gymnastics, vegetarianism, kettlebell training, fasting, CrossFit, Paleo, and so on, until he realized (or decided) that strength training fit best with the ideas of continuous, measurable self improvement.

At BarBend his writing focuses a little more on nutrition and long-form content with a heaping dose of strength training. His underlying belief is in the middle path: you don’t have to count every calorie and complete every workout in order to benefit from a healthy lifestyle and a stronger body. Plus, big traps are cool.

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